TABLE 2.
Plasma concentrations of tryptophan metabolites and ratios in OC users vs. nonusers with adequate (PLP = 31–70 nmol/L) and low (PLP ≤30 nmol/L) vitamin B-6 status1
| Adequate vitamin B-6 status |
Low vitamin B-6 status |
|||
| Nonusers (n = 11) | OC users (n = 93) | Nonusers (n = 11) | OC users (n = 18) | |
| Tryptophan, μmol/L | 55.4 ± 9.13 | 63.6 ± 11.4 | 59.6 ± 8.13 | 64.3 ± 12.6 |
| Kyn, μmol/L | 1.18 ± 0.29 | 1.27 ± 0.24 | 1.08 ± 0.18 | 1.34 ± 0.26 |
| HK, nmol/L | 29.4 ± 10.9 | 33.8 ± 9.88 | 35.0 ± 15.0 | 35.5 ± 13.8 |
| KA, nmol/L | 26.7 ± 11.2 | 29.6 ± 10.0 | 19.7 ± 4.51 | 24.4 ± 6.99 |
| XA, nmol/L | 7.90 ± 4.56 | 14.2 ± 8.13 | 6.48 ± 2.08 | 14.1 ± 7.95* |
| AA, nmol/L | 12.8 ± 2.31 | 13.4 ± 12.1 | 12.8 ± 1.82 | 11.1 ± 3.77 |
| HAA, nmol/L | 18.4 ± 6.00 | 32.4 ± 12.1* | 15.8 ± 4.44 | 26.2 ± 10.1* |
| Quinolinic acid, nmol/L | 253 ± 70.5 | 346 ± 107 | 256 ± 43.6 | 326 ± 62.6* |
| Nicotinamide, nmol/L | 261 ± 217 | 387 ± 152 | 228 ± 111 | 449 ± 225* |
| N1-methylnicotinamide, nmol/L | 142 ± 92.1 | 150 ± 73.5 | 131 ± 96.2 | 174 ± 87.5 |
| Ratios | ||||
| HK:KA | 1.22 ± 0.64 | 1.21 ± 0.38 | 1.88 ± 0.94 | 1.54 ± 0.65 |
| HK:AA | 2.42 ± 1.34 | 2.65 ± 0.86 | 2.87 ± 1.56 | 3.68 ± 2.49 |
| HK:XA | 4.35 ± 2.38 | 3.08 ± 1.88 | 6.18 ± 4.18 | 3.33 ± 1.96 |
| HK:HAA | 1.63 ± 0.51 | 1.11 ± 0.32 | 2.35 ± 1.05 | 1.50 ± 0.73 |
| HK:Kyn | 25.4 ± 9.89 | 26.7 ± 5.97 | 31.7 ± 9.46 | 26.7 ± 8.62 |
1
Values are means ± SDs. Multivariate ANOVA was performed separately for adequate and low vitamin B-6 status. *Different from nonusers within vitamin B-6 status, adjusted P < 0.05. Adjustment for multiple testing was based on the Sidak method. AA, anthranilic acid; HAA, 3-hydroxyanthranilic acid; HK, 3-hydroxykynurenine; KA, kynurenic acid; Kyn, kynurenine; OC, oral contraceptive; PLP, pyridoxal 5′-phosphate; XA, xanthurenic acid.